EP0592834A1 - Injecteur de combustible haute-pression avec arrêt de plongeur amorti - Google Patents

Injecteur de combustible haute-pression avec arrêt de plongeur amorti Download PDF

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Publication number
EP0592834A1
EP0592834A1 EP93114908A EP93114908A EP0592834A1 EP 0592834 A1 EP0592834 A1 EP 0592834A1 EP 93114908 A EP93114908 A EP 93114908A EP 93114908 A EP93114908 A EP 93114908A EP 0592834 A1 EP0592834 A1 EP 0592834A1
Authority
EP
European Patent Office
Prior art keywords
plunger
spring
fuel injector
keeper
injector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP93114908A
Other languages
German (de)
English (en)
Other versions
EP0592834B1 (fr
Inventor
Lester L. Peters
David P. Genter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cummins Inc
Original Assignee
Cummins Engine Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cummins Engine Co Inc filed Critical Cummins Engine Co Inc
Publication of EP0592834A1 publication Critical patent/EP0592834A1/fr
Application granted granted Critical
Publication of EP0592834B1 publication Critical patent/EP0592834B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F02M57/022—Injectors structurally combined with fuel-injection pumps characterised by the pump drive
    • F02M57/023—Injectors structurally combined with fuel-injection pumps characterised by the pump drive mechanical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F02M57/021—Injectors structurally combined with fuel-injection pumps the injector being of valveless type, e.g. the pump piston co-operating with a conical seat of an injection nozzle at the end of the pumping stroke
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F02M57/022—Injectors structurally combined with fuel-injection pumps characterised by the pump drive
    • F02M57/023—Injectors structurally combined with fuel-injection pumps characterised by the pump drive mechanical
    • F02M57/024—Injectors structurally combined with fuel-injection pumps characterised by the pump drive mechanical with hydraulic link for varying the piston stroke
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/30—Varying fuel delivery in quantity or timing with variable-length-stroke pistons

Definitions

  • the present invention is related to the field of high pressure fuel injectors for internal combustion engines of the type having a plunger assembly, with a plurality of plungers, that is mounted within a central bore within the body of the fuel injector for reciprocal movement. More specifically, the invention relates to such a fuel injector where the plunger assembly has an upper plunger and a lower plunger mounted for reciprocal motion within the central bore and a variable volume injection chamber in said lower end of the central bore between the injection orifice and a bottom end of the lower plunger.
  • a fuel injector of the initially mentioned type is known, for example, from U.S. Patent Nos. 4,721,247 and 4,986,472 (which are owned by the assignee of this application). While an improvement over then existing fuel injections systems, such fuel injectors have a return spring which serves to draw the lower injection plunger upwardly into engagement with an intermediate plunger to force these plungers and an upper plunger together after completion of an injection cycle until metering and timing has commenced for the next cycle, and thereby, establishing a preload force which must be overcome to meter timing fluid into the timing chamber (between the upper and intermediate plungers) to vary the advancement of injection timing.
  • a second object of the present invention is to provide an improved high pressure fuel injector for internal combustion engines which can achieve the preceding object by providing for the return stroke of the lower plunger to be limited to significantly less than that of the stroke of the upper plunger of the plunger assembly.
  • Yet another object of the present invention is to provide a high pressure fuel injector for internal combustion engines that uses an improved lower plunger and return spring arrangement which affords a cushioned stopping of return movement of the lower plunger.
  • an improved high pressure fuel injector for internal combustion engines of the type having a plunger assembly, with a plurality of plungers, that is mounted within a central bore within the body of the fuel injector for reciprocal movement, the plunger assembly having an upper plunger and a lower plunger mounted for reciprocal motion within the central bore and a variable volume injection chamber in the lower end of the central bore between the injection orifice and a bottom end of the lower plunger.
  • the retainer 5 receives the injector cup 3c, supported on shoulder 5a with spray nozzle 4 projecting from the bottom end thereof.
  • the lower barrel part 3b is received in the retainer 5 supported on the injector cup 3c.
  • retainer 5 secures the injector cup 3c and lower barrel part 3b together in end-to-end fashion with the upper barrel part 3a.
  • the top end of the retainer 5 has internal threads 6a by which it is connected to external threads 6b on the bottom end of upper injector barrel part 3a, as shown.
  • a central bore extends through the parts 3a-3c of the injector body 3 of the fuel injector 1, and a reciprocating plunger assembly 7 is disposed in this central bore.
  • the plunger assembly 7 includes three plungers. An upper plunger 8, an injection plunger 9 and a timing plunger 10 disposed therebetween.
  • the fuel injector 1 is part of a fuel injection system having a plurality of such injectors, each of which is driven by a rotating camshaft (not shown) via a conventional drive train assembly which includes a link 11 that causes the plunger assembly 7 to reciprocate in synchronism therewith.
  • the difference in structure and operation of the injector of the present invention lies in the manner and means by which the return stroke of the plunger assembly 7, from the Fig. 1 position to the Fig. 2 position, is achieved.
  • Fig. 1 at the end of the injection stroke of plunger assembly 7, after a hold down phase, all of the fuel metered into the injection chamber 12 (Fig. 2) has been delivered into the combustion chamber of the engine cylinder.
  • the lower plunger In this position, the lower plunger is held seated in the bottom end of the injection cup 3, against the force of a now-compressed return spring S, by the end-to-end contact between the plungers 8-10 which have been fully driven into the injector body by the action of the link 11 and the drive train associated therewith.
  • the return spring S is captured between an upper spring keeper 14 and a lower spring keeper 16, both of which are of a stepped washer-like construction.
  • the upper spring keeper 14 may be annular and sized to fit axially over the land 9b but not the land 9c (lands 9b, 9c, and 9d would be of successively greater diameters), or horseshoe-shaped (as shown for spring keeper 14'in Fig. 4) and slid radially onto a reduced diameter portion 9a of lower plunger 9 that is located between the pair of lands 9b, 9c, and retained in place by a retainer ring 17 and spring clip 18, as shown most clearly in Fig. 2a.
  • Upper spring keeper 14 also has a flange 14a against which the upper end of the spring S abuts.
  • This flange 14a has a notch 15 which provides a path for draining timing fluid and fuel (which is either released by the timing plunger or leaks upwardly through the clearance between the lower plunger 9 and the lower injector barrel part 3b) to the engine drain flowpath.
  • this function can be served by the gap (15') between the legs of the horseshoe shape.
  • the lower spring keeper 16 has a through-hole 16a that is large enough to pass over the lands 9b and 9c and has a counterbore 16b (Fig. 1) at its lower end within which a larger intermediate land 9d is able to be received, as shown in Figs. 2 and 2a.
  • the lower spring keeper 16 also has an annular flange 16c that abuts on the bottom of a spring recess 20 formed in lower barrel part 3b of the injector body 3 and carries the bottom end of spring S.
  • the plunger assembly In the Figure 1 position, the plunger assembly is in its innermost or lowermost position in which the spring S is compressed by the force applied to lower plunger 9 by link 11 via upper plunger 8, timing plunger 7. At this point in the injection cycle, injection of fuel into the engine has been completed and any remaining timing fluid drained from between the upper plunger 8 and the timing plunger 10, in a manner that forms no part of this invention.
  • a return spring 22 raises the upper plunger 8 and the timing plunger 10 is drawn upwardly with it (or a time plunger return spring can be provided between the upper spring keeper 14 and the bottom of timing plunger 10).
  • a stop surface 24 is provided (which, in the illustrated embodiment, is provided on an inner wall of upper barrel 3a) that limits upward movement of the upper spring keeper 14 that can be produced by the spring S.
  • the stroke of lower plunger 9 can be limited to an amount which is just sufficient to produce an injection chamber 12 that has a maximum volume which essentially equals that of the maximum dosage of fuel that it will be necessary for the injector to inject. In this way, detonation of the fuel within the injector can be avoided.
  • the next injection cycle commences with an injection timing mode in which timing fluid is supplied via a timing fluid supply passage to the reduced diameter lower end of upper plunger 8, and in a conventional manner, the supplied timing fluid displaces the timing plunger 10, filling a variable volume timing chamber between the upper and timing plungers 8, 10 with an amount of timing fluid designed to appropriately adjust the timing at which injection of fuel from nozzle 4 commences.
  • spring S is unable to apply a load to the timing plunger 10, via injection and metering plunger 9, due to the travel of plunger 9 having been stopped, additional advantages beyond that noted above are obtained. That is, due to unloading of the timing plunger 10, the timing fluid metering pressure can be reduced during low speed operation and the spring force tolerance effect on injection timing accuracy is eliminated.
  • the appropriate quantity of fuel to be injected is metered into injection chamber 12.
  • the injection stroke is commenced with the upper plunger 8 and timing plunger 10 moving downwardly in unison due to the hydraulic link formed between them by the timing fluid in the timing chamber.
  • the lower plunger 9 commences its movement toward the Fig. 1 position and fuel is injected from chamber 12 into the combustion chamber of the engine.
  • this portion of the injection cycle can proceed in the usual manner unaffected by the cushioned stop, spring arrangement.
  • the maximum quantity of fuel that must be able to be delivered by a fuel injector will vary between engines of differing designs and engine uses. Furthermore, in many respects, it would be as undesirable to use an injector of the present invention which is designed for a significantly larger maximum dosage requirement than will be needed in a particular engine application as it would be to use one which is designed for the intended maximum dosage requirements but is of a construction where the lower plunger executes the full stroke of the upper plunger. Thus, it would be advantageous if it were not necessary to have a number of different size injectors to meet all of the various engine needs, and instead, to be able to adapt a single fuel injector to various requirements through only minor modifications. Thus has been achieved in accordance with another feature of the present invention.
  • spring keepers 14, 16 and spring keepers 14', 16' are most easily seen from a comparison of Figs. 2a and 3. From such a comparison, it can be seen that upper spring keeper 14' has a flange 14'a of a height/thickness which is substantially less than that of flange 14a, thereby allowing the top of spring S to expand further into the upper barrel part 3a. Also apparent is the fact that the counterbore 16'b is significantly deeper than counterbore 16, thereby causing the land 9d of the plunger 9 to move further upward before it engages the lower keeper 16' and is brought to a cushioned stop by the spring S; however, the amount of lash or play L remains the same.
  • spring S With regard to spring S, the same spring will usually be able to act on plunger 9 even though a stroke length adjustment is made, as mentioned above, solely through use of a different injector cup 3c.
  • spring keepers 14', 16' instead of spring keepers 14, 16 (compare Figs. 2a and 3)
  • Fig. 5 it can be seen that the spring recess 20'' has a smaller diameter and the lower end of the spring S'' (which is also of reduced diameter) is seated on an upper flanged portion 16''d of the lower spring keeper 16'' instead of on the flange 16c''. Additionally, the flange 16c'' of the lower spring keeper is shown received in a damping chamber D.
  • the supplemental cushioning effect is produced by providing a damping spring 26 which acts between the lower spring keeper 16''' for the return spring S''' ⁇ and a second upper keeper 28.
  • This second upper keeper for the damping spring 26 engages a stop surface 24'' on the upper barrel part 3'''a. It is noted that the stop surface 24''' is shifted downwardly relative to the position of stop surface 24 in the prior embodiments since the upper keeper no long requires a stop other than that provided by the 9'''b land of the lower plunger 9'''.
  • the present invention provides an improved high pressure fuel injector for internal combustion engines in which the problem of large quantities of air being drawn into the injector from the combustion chamber during the retraction stroke can be avoided by limiting the return stroke of the lower plunger to a distance that is significantly less than that of the stroke of the upper plunger of the plunger assembly. Furthermore, it can be seen how the present invention affords a cushioned stopping of the return movement of the lower plunger and is also able to allow fuel injectors, having different maximum injectable charge capabilities, to be produced from the same basic set of components without requiring more than the return spring assembly and injector nozzle to be changed.
  • the present invention will find applicability in a wide range of fuel injection systems for internal combustion engines, particularly diesel engines.
  • the invention will be especially useful where it is desired to have a single fuel injection system that is able to be easily and inexpensively adapted to meet the fuel dosage requirements of a range of different engines and engine use conditions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)
EP93114908A 1992-09-16 1993-09-16 Injecteur de combustible haute-pression avec arrêt de plongeur amorti Expired - Lifetime EP0592834B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US945390 1992-09-16
US07/945,390 US5299738A (en) 1992-09-16 1992-09-16 High pressure fuel injector with cushioned plunger stop

Publications (2)

Publication Number Publication Date
EP0592834A1 true EP0592834A1 (fr) 1994-04-20
EP0592834B1 EP0592834B1 (fr) 1997-07-16

Family

ID=25483028

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93114908A Expired - Lifetime EP0592834B1 (fr) 1992-09-16 1993-09-16 Injecteur de combustible haute-pression avec arrêt de plongeur amorti

Country Status (4)

Country Link
US (1) US5299738A (fr)
EP (1) EP0592834B1 (fr)
JP (1) JPH0826831B2 (fr)
DE (1) DE69312204T2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19833692C2 (de) * 1997-08-22 2001-01-11 Cummins Engine Co Inc Injektoreinheit mit Zeitsteuerplungerkolben mit festem Anschlag

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5611317A (en) * 1995-08-09 1997-03-18 Cummins Engine Company, Inc. Open nozzle fuel injector having drive train wear compensation
AT409787B (de) * 1996-08-23 2002-11-25 Steyr Daimler Puch Ag Kraftstoffeinspritzaggregat für dieselmotoren
US5887790A (en) * 1996-11-07 1999-03-30 Caterpillar Inc. Unit injector having a cavitation pressure control mechanism
US5868112A (en) * 1996-12-19 1999-02-09 Cummins Engine Company, Inc. Deep angle injection nozzle and piston having complementary combustion bowl
US5845623A (en) * 1997-06-27 1998-12-08 Cummins Engine Company, Inc. Variable volume chamber device for preventing leakage in an open nozzle injector
US6029902A (en) * 1998-03-26 2000-02-29 Cummins Engine Company, Inc. Fuel injector with isolated spring chamber
US5934254A (en) * 1998-03-27 1999-08-10 Cummins Engine Company, Inc. Top stop assembly for a fuel injector
US6732703B2 (en) 2002-06-11 2004-05-11 Cummins Inc. Internal combustion engine producing low emissions
US7210448B2 (en) * 2002-06-11 2007-05-01 Cummins, Inc. Internal combustion engine producing low emissions
US7007860B2 (en) * 2002-08-30 2006-03-07 Caterpillar Inc. Plunger cavity pressure control for a hydraulically-actuated fuel injector
US7849836B2 (en) * 2008-10-07 2010-12-14 Caterpillar Inc Cooling feature for fuel injector and fuel system using same
US8677970B2 (en) 2011-03-17 2014-03-25 Cummins Intellectual Property, Inc. Piston for internal combustion engine

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2792259A (en) * 1953-07-03 1957-05-14 Int Harvester Co Fuel injector for internal combustion engines
FR2214049A1 (fr) * 1973-01-15 1974-08-09 Cummins Engine Co Inc
US5033442A (en) * 1989-01-19 1991-07-23 Cummins Engine Company, Inc. Fuel injector with multiple variable timing
EP0460693A1 (fr) * 1990-06-07 1991-12-11 Cummins Engine Company, Inc. Injecteur à combustible à haute pression

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4149506A (en) * 1975-10-29 1979-04-17 Cummins Engine Company, Inc. Fuel injector
US4471909A (en) * 1981-12-18 1984-09-18 Cummins Engine Company, Inc. Miniaturized unit fuel injector
US4721247A (en) * 1986-09-19 1988-01-26 Cummins Engine Company, Inc. High pressure unit fuel injector
US4986472A (en) * 1989-09-05 1991-01-22 Cummins Engine Company, Inc. High pressure unit fuel injector with timing chamber pressure control
US5040727A (en) * 1990-07-19 1991-08-20 Cummins Engine Company, Inc. Unit fuel injector with plunger minor diameter floating sleeve

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2792259A (en) * 1953-07-03 1957-05-14 Int Harvester Co Fuel injector for internal combustion engines
FR2214049A1 (fr) * 1973-01-15 1974-08-09 Cummins Engine Co Inc
US5033442A (en) * 1989-01-19 1991-07-23 Cummins Engine Company, Inc. Fuel injector with multiple variable timing
EP0460693A1 (fr) * 1990-06-07 1991-12-11 Cummins Engine Company, Inc. Injecteur à combustible à haute pression

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19833692C2 (de) * 1997-08-22 2001-01-11 Cummins Engine Co Inc Injektoreinheit mit Zeitsteuerplungerkolben mit festem Anschlag

Also Published As

Publication number Publication date
DE69312204T2 (de) 1998-03-05
EP0592834B1 (fr) 1997-07-16
JPH06193532A (ja) 1994-07-12
DE69312204D1 (de) 1997-08-21
JPH0826831B2 (ja) 1996-03-21
US5299738A (en) 1994-04-05

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